The invention relates to a microdrive for the activation of latches with a gear assigned to the latch housing with a worm drive wheel and a motor which has a lock which prevents the gear from rolling back.
In drives for the electrical opening of latches, especially in microdrives, for cost reasons motors are predominantly energized in such a way that they can drive the gear with the worm drive wheel in a single direction. A resetting of the gear after depletion of the energization of the motor is not desired, it would impede the continued running of the microdrive. As the known gears, at least in part, are spring-loaded, the worm gear wheels of the gear are reset without a lock after switch-off the power and the drive. As stated, this is disadvantageous and undesirable. For generally known microdrives, the rolling back of the gear against the drive direction is prevented by a free-wheel diode being attached to the motor, by means of which the motor is short-circuited and thus brakes when rolling back. This prevents the voltages arising upon switch-off of the motor and the rolling back impelled by the gear having a negative impact. The direction of the voltage arising results according to the Lenzschen rule. The free-wheel diode prevents the induced power on the switching element, i.e. the motor, generating a high voltage and endangering the motor in certain circumstances. While the free-wheel diodes used are a cost-effective component in principle, the necessary soldering process and the making available of the materials for soldering of the free-wheel diode is extremely expensive. Consequently, a solution is sought here.